OpenVPN is a full-featured open source SSL VPN solution that accommodates a wide range of configurations, including remote access, site-to-site VPNs, Wi-Fi security, and enterprise-scale remote access solutions with load balancing, failover, and fine-grained access-controls. Starting with the fundamental premise that complexity is the enemy of security, OpenVPN offers a cost-effective, lightweight alternative to other VPN technologies that is well-targeted for the SME and enterprise markets.

This page is designed to provide an applied-level of support. The OpenVPN HowTo has lots of great examples and configuration option.

Help with creating a VPN which connects multiple lans. Server and clients have lans behind them. This will help you understand how to use the route, push route, and iroute commands.